SITTING behind the wheel for long stretches and getting your meals at roadhouses is evidently not great for your waistline.

The top two occupations in a new study into the most obese jobs involve driving, the Huffington Post reports.

The study, which used data from 37,626 people in Washington State, found that truck driving had the highest prevalence of obese workers (38.6 per cent) and transportation/moving was close behind (37.9 per cent).

People in the protective services were third, with exactly a third of the industry's workers considered obese according to their Body Mass Index (BMI).

But because BMI measurements don't distinguish between a person who is heavy because of fat and a person who is heavy because of muscle mass, it's likely that the protective services personnel (including fire fighters and cops) aren't obese as their BMI suggests.

"Workers with physically demanding jobs may be more physically fit and have a higher BMI because of increased muscle mass," the researchers wrote in the study.

"For example, protective services (e.g., firefighters, police officers) had a high prevalence of obesity but also had the highest proportion of vigorous LTPA [leisure time physical activity]."

Cleaners, like Kenny, were found to be among the fattest.Source:News Limited

Here is the ranking of obesity prevalence, from most to least, based on occupational group: